Procatalyst component based on a transition metal compound on a carrier of magnesium chloride and manganese halide

ABSTRACT

Olefin polymerization catalysts the procatalyst component of which comprises a transition-metal compound on a magnesium chloride support material are known to all. Now the procatalyst component has been improved by incorporating a manganese (II) halide into it at a rate of at minimum approx. 0.1% and at maximum approx. 50% of the total molar amount of magnesium chloride and manganese (II) halide. The new polymerization catalyst has, among other things, the excellent special property that it yields a polyolefin with a broad molecular weight distribution.

The invention relates to an olefin polymerization catalyst theprocatalyst component of which comprises a transition-metal compound ona support material of magnesium chloride. The invention also relates toa method for preparing a procatalyst component for an olefinpolymerization catalyst of the said type, wherein

a) a magnesium chloride and a lower alcohol are contacted and themixture is melted,

b) the molten mixture is atomized, and it is solidified by cooling toproduce support material particles, and

c) the support material particles are caused to react with atransition-metal compound.

Furthermore, the invention relates to the use of an olefinpolymerization catalyst of the said type for the preparation ofpolypropylene, and preferably a polypropylene with a broad molecularweight distribution.

α-olefins are often polymerized using a Ziegler-Natta catalyst systemmade up of a so-called procatalyst and a cocatalyst. Of these, theprocatalyst component is based on a compound of a transition metalbelonging to any of Groups IVA-VIII in the Periodic Table of theElements, and the cocatalyst component is based on an organometalliccompound of a metal belonging to any of Groups IA-IIIA in the PeriodicTable of the Elements (the groups are defined according to Hubbard, i.e.IUPAC). The catalyst system may also include a support material on whichthe transition-metal compound is deposited and an internal electrondonor which enhances and modifies the catalytic properties and isdeposited on the support material together with the transition-metalcompound. In addition, a separate so-called external electron donor canalso be used together with the procatalyst and the cocatalyst.

The Ziegler-Natta catalysts used for polypropylene polymerizationusually produce a polymer having a narrow molecular weight distribution.This material is very suitable for injection molding purposes. However,there are several uses in which a broad molecular weight distribution isrequired. Especially if a higher melt strength is desired, a wider rangeof polymer chain lengths would be an advantage. If it is assumed thatpolymerization takes place at specific so-called active sites in thecatalyst, active sites of the same type will produce a polymer materialof the same type, in which case the uniformity is seen as a narrowmolecular weight distribution. Since a broader molecular weightdistribution is required for a number of uses of polypropylene, effortshave been made to prepare catalysts with active sites of a variety oftypes.

JP application publication 79037911 describes the preparation of apolyolefin having a wide molecular weight distribution by using anactive and new procatalyst which is made up of a titanium and/orvanadium compound on a support material. The first component is obtainedby treating aluminum oxide with sulfur dioxide, and the other componentcontains a magnesium halide, a manganese halide, and an organic compoundof a metal such as aluminum or zinc, e.g. MgCl₂ MnCl₂ --Al(OR₃).

By this known method it has been possible, for example, to improve thecasting properties of the polymer, but the process for preparing thecatalyst is too complicated and unconventional in order to becommercially usable.

The object of the present invention is to provide a catalyst comprisinga transition-metal compound on a magnesium chloride support material forproducing polyolefins having a broad molecular weight distribution.Another aim is a maximal catalyst activity and a suitable catalystmorphology, which will also be reflected in the morphology of thepolymer product. The invention also aims at an improved method for theproduction of an olefin polymerization catalyst of the said type.

These objects have now been achieved with a new olefin polymerizationcatalyst, the procatalyst component of which has been prepared by (a)contacting magnesium chloride and a lower alcohol and melting themixture, (b) atomizing the molten mixture and solidifying it by coolingto produce support material particles, (c) reacting the support materialparticles with a transition metal compound, characterized by addingmanganese (II) halide at stage (a) at a rate of a minimum ofapproximately 0.1% and a maximum of approximately 50% of the total molaramount of magnesium chloride and manganese (II) halide. The objects havefurther been achieved with a new method for the production of aprocatalyst component for an olefin polymerization catalyst, wherein (a)magnesium chloride and a lower alcohol are contacted, and the mixturemelted, (b) the molten mixture is atomized, and solidified by cooling toproduce support material particles, and (c) the support materialparticles are reacted with a transition metal component, characterizedin that manganese (II) halide is added during step (a) at a rate at aminimum of approximately 0.1% and a maximum of approximately 50% of thetotal molar amount of magnesium chloride and manganese (II) halide.

It has thus been realized that an olefin polymerization catalyst moresuitable for the above-mentioned use is obtained if manganese (II)halide is incorporated into its magnesium chloride support material at arate of at minimum approx. 0.1%, and at maximum approx. 50%, of thetotal molar amount of magnesium chloride and manganese (II) halide. Itis preferable that the minimum concentration of manganese (II) halide isapprox. 5% of the total molar amount of magnesium chloride and manganese(II) halide. The maximum concentration of manganese (II) halide ispreferably approx. 40% of the total molar amount of magnesium chlorideand manganese (II) halide. It is even more preferable that the maximumconcentration of manganese (II) halide is less than 30%, and preferablyapprox. 10%, of the said the said total molar amount.

The active part of the catalyst, i.e. the transition-metal compound, ispreferably a titanium compound, such as a titanium alkoxide, a titaniumalkoxyhalide or a titanium halide, or a vanadium compound, such as avanadium oxyhalide or a vanadium halide. The most preferabletransition-metal compound is titanium tetrachloride.

The manganese (II) halide is selected so that with respect to its ionradii it fits as well as possible into the crystal lattice of magnesiumchloride. It has been observed that the most advantageous manganese (II)halide is manganese chloride. The said advantageous concentrations havespecifically been measured using manganese (II) chloride, but similarresults are probably attainable also using other manganese (II) halides.

A preferred composition, based on weight, of the procatalyst componentfor the polymerization catalyst according to the invention is, notincluding the organometallic cocatalyst used in the polymerization, asfollows: magnesium 10-20%, manganese 1-10%, titanium 2-4%, and chlorine45-60%, calculated from the total weight of the supported procatalystcomponent.

According to one embodiment of the invention, on the magnesium chloridesupport material there is, in addition to the transition-metal compound,also an internal donor, which is preferably an aromatic ester of thetype of di-isobutyl phthalate. Benzoic acid esters are also possible.The concentration of this internal donor may be 10-25% of the weight ofthe procatalyst component in the catalyst.

The catalyst according to the invention preferably also contains anorganometallic cocatalyst, which is preferably a trialkyl aluminum,preferably triethyl aluminum. In order to improve, for example,stereoselectivity, a so-called external donor may also be added to thecatalyst; the external donor may be silane, cineole or ether, preferablycyclohexyl-methylmethoxysilane, cineole, or diphenyl-dimethoxysilane.

The solid part of the catalyst according to the invention is in the formof substantially spherical particles having a diameter within a range ofapprox. 100-400 μm.

As was already mentioned, the invention also relates to a method for thepreparation of a procatalyst component for an olefin polymerizationcatalyst. In the method, magnesium chloride and a lower alcohol arecontacted and melted, the molten mixture is atomized and solidified bycooling to produce support material particles, and the support materialparticles are reacted with a transition-metal compound to produce anactive procatalyst. In the invention it has been realized that a broadermolecular weight distribution can be obtained by adding to the magnesiumchloride and the lower alcohol a manganese (II) halide at a rate of atminimum approx. 0.1% and at maximum approx. 50% of the total molaramount of magnesium chloride and manganese (II) halide. This additiontakes place before the solidification and thus yields a homogenousprocatalyst doped with manganese.

In the first step, i.e. step a), the magnesium chloride and the loweralcohol are contacted and the mixture is melted, and in the second step,i.e. in step b), the melt is atomized and it is solidified by cooling itto produce support material particles. These steps a) and b) arepreferably carried out by suspending a finely-divided magnesium chlorideand a finely-divided manganese (II) halide, preferably manganese (II)chloride, into an inert, heat-resistant medium. Then a lower alcohol isadded to the suspension and the suspension is heated until the mixturemade up of the said salts and alcohol melts, forming melt drops in themedium. After the said steps, the medium with its melt drops iscontacted with a cold liquid, which dissolves the medium and solidifiesthe melt drops into finished support material particles.

As is evident from the description of the catalyst, compounds oftitanium and vanadium are preferred transition-metal compounds, and themost preferred one is titanium tetrachloride. Manganese (II) chloride isa preferred manganese (II) halide.

Manganese (II) halide (preferably chloride) is preferably added to stepa) at a rate of at minimum 5% of the total molar amount of magnesiumchloride and manganese (II) halide (preferably chloride). Manganese (II)halide (preferably chloride) is added to step a) at a rate of at maximumapprox. 40% of the total molar amount of magnesium chloride andmanganese (II) halide (preferably chloride). It is most preferable toadd manganese (II) chloride to step a) at a rate of at maximum approx.30% and preferably approx. 10% of the total molar amount of magnesiumchloride and manganese (II) chloride.

The lower alcohol used in step a) is preferably methanol and/or ethanol,and most preferably ethanol.

The solid support material obtained from step b) in the form orparticles is caused to react with a transition-metal compound in stepc). As was already mentioned, the most preferred transition-metalcompound is titanium tetrachloride. According to one preferredembodiment, step c) is carried out by causing the support materialparticles to react not only with the transition-metal compound but alsowith an internal electron donor, in which case the electron donor usedis preferably an aromatic ester such as di-isobutyl phthalate.

According to one embodiment, the catalyst according to the invention isused for producing a polypropylene having a broad molecular weightdistribution. In this case, the said procatalyst is combined with anorganometallic cocatalyst and preferably also an external donor, whichmay be, for example, silane, cineole, ether or other such external donorcommonly known in the art.

Embodiment examples 3, 4 and 5, as well as comparison examples 1 and 6,are presented below in order to elucidate the invention.

EXAMPLES

Examples 1 and 6 are comparison examples, in which the molarconcentrations of manganese are respectively 0 and 100%. In thecorresponding embodiment examples 2, 3, 4, and 5, the manganeseconcentrations in the support material were respectively 3, 10, 30, and60 mol-%.

The accompanying FIGS. 1-14 depict the following:

FIG. 1. The morphology of the MgCl₂.EtOH support material doped with 3%MnCl₂.

FIG. 2. The morphology of the MgCl₂.EtOH support material doped with 10%MnCl₂.

FIG. 3. The morphology of the MnCl₂.EtOH support material.

FIG. 4. The mean particle diameter of the support material as a functionof the Mn concentration (mol-%) in MgCl₂.

FIG. 5. The correlation between the molar percentage of the manganeseadded and the molar percentage detected in the product and in thecatalyst.

FIG. 6. The proportion of donor bound by the metals (Mg+Mn) in theMn-doped catalyst.

FIG. 7. The X-ray diffraction pattern of a Ziegler-Natta catalyst dopedwith 10% Mn in a MgCl₂ support material.

FIG. 8. The activities of Mn-doped Ziegler-Natta catalysts.

FIG. 9. The isotacticities (A) and isotactic indices (B) of polymersproduced using Mn-doped catalysts.

FIG. 10. The bulk density (B) and the percentage (A) of coarse material(d>1 mm) of PP material, as a function of the molar percentage ofmanganese in the procatalyst.

FIG. 11. The particle size distribution of a polymer sample producedusing a catalyst doped with 30% manganese.

FIG. 12. Molecular weights of the polymer samples as a function of themolar percentage of manganese in the procatalyst support material.

FIG. 13. Polydispersity of the polymer samples as a function of themolar percentage of manganese in the procatalyst support material.

FIG. 14. Comparison between the molecular weight distribution (MWD) of aPP sample produced using a conventional catalyst and the molecularweight distribution of a PP sample produced using a Mn-doped catalyst.

PREPARATION OF SUPPORT MATERIAL

1-30 g of magnesium chloride and manganese (II) chloride were suspendedat room temperature into 600 ml of silicone oil in a reactor. Agitationwas continued for half an hour in order to achieve equilibriumconditions. Thereafter 56 ml of dry ethanol was added, drop by drop, andthe mixture was gradually heated to 40° C. The solution was againallowed to reach an equilibrium, whereafter the temperature was raisedto 123°-132° C. Thereafter, ethanol was added until the salt mixturebecame liquid. Then vigorous agitation was used in order to distributethe liquid melt drops evenly into the silicone oil. When a clear saltmelt had been achieved, the hot silicone oil mixture was siphonedthrough a teflon tube into a reactor containing 1 liter of cold heptane(-30° C.). The melt drops of the metal salt mixture solidified in thiscold solution. In order to remove the silicone oil, the solids werewashed three times with 600 ml of heptane. Ultimately, the supportmaterial was vacuum dried.

In the preparation of the support material it became evident thatmanganese (II) chloride had a lower solubility in ethanol than hadmagnesium chloride. Ethanol must be added to certain mixtures in orderto bring the salt into a molten state. Approx. twice as much ethanol hadto be added in order to bring mixtures containing more than 10 mol-%manganese into a molten state in a silicone bath. The chemicals addedare listed in Table 1, and Table 2 shows the magnesium and manganeseconcentrations in the support material produced. The molar percentagesin Table 2 were calculated from the total molar amount of the metals,and the corresponding weight percentages from the total weight of thesupport material.

                  TABLE 1                                                         ______________________________________                                        Chemicals added in the production of support materials                                    MgCl.sub.2 MnCl.sub.2                                                                             Ethanol                                       Example     added (g)  added (g)                                                                              added (ml)                                    ______________________________________                                        1 (comparison)                                                                            30.0       0        56                                            2 (embodiment)                                                                            29.1       1.2      56                                            3 (embodiment)                                                                            27.0       4.0      101                                           4 (embodiment)                                                                            21.0       12.0     56                                            5 (embodiment)                                                                            12.0       24.0     95                                            6 (comparison)                                                                            0          39.6     92                                            ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                        Calculated chemical composition of the support material                       as compared with the concentrations obtained in the product                          Calcu-                                                                        lated   Weight %  Mol-%  Weight-%                                                                              Mol-%                                        mol-%   Mn de-    Mn de- Mg de-  Mg de-                                Example                                                                              Mn      tected    tected tected  tected                                ______________________________________                                        1 (comp.)                                                                             0      0         0      10.4    100.0                                 2 (emb.)                                                                              3      0.8       3.1    10.4    96.9                                  3 (emb.)                                                                             10      1.6       10.0   6.5     90.1                                  4 (emb.)                                                                             30      6.8       29.2   7.3     70.8                                  5 (emb.)                                                                             60      14.3      57.9   4.6     42.1                                  6 (comp.)                                                                            100     28.8      100.0  0.0     0.0                                   ______________________________________                                    

The morphology of the support material obtained was such that a highermanganese amount added to the salt mixture hampered the bringing of themix into a liquid or molten state. The molten material was in this casealso more viscous. Since the mixing conditions in the silicone bath inthe different examples were identical, a higher melt viscosity alsoyielded larger support material particles. This increase in the particlediameter continued up to a manganese concentration of 30%. Thereafterthe liquid melt drops were no longer capable of forming sphericalparticles. This change in particle morphology can be seen in FIGS. 1-3.The first figure shows the morphology of a material doped with 3 percentmanganese. The morphology of this material resembles that of aconventional magnesium chloride support material, and the mean particlediameter is approx. 50 μm. The next of these figures shows enlargedparticles of a material doped with 10% manganese, and the last one showsa crystalline material prepared from pure manganese (II) chloride. Table3 lists the mean particle sizes, and they are also shown graphically inFIG. 4. Table 3 also shows the general morphological character and colorof the products.

                  TABLE 3                                                         ______________________________________                                        Mean particle size diameter of the support material as                        a function of the mol-% of Mn in MnCl.sub.2, as well as the color             and morphology of the material                                                       Mol-%                                                                         Mn in                                                                         support   Catalyst particle   Morphol-                                 Example                                                                              material  diameter (μm)                                                                           Color  ogy                                      ______________________________________                                        1 (comp.)                                                                             0         50          W      S                                        2 (emb.)                                                                              3         50          SG     S                                        3 (emb.)                                                                             10        200          SG     A                                        4 (emb.)                                                                             30        300          LT     S                                        5 (emb.)                                                                             60         50          T      G                                        6 (comp.)                                                                            100        5           GR     C                                        ______________________________________                                         Color:                                                                        W = white                                                                     SG = slightly green                                                           LT = light turquoise                                                          T = turquoise                                                                 GR = green                                                                    Morphology:                                                                   S = spherical                                                                 A = agglomerate                                                               G = granular                                                                  C = crystalline                                                          

Production of Procatalyst

0.1 mol of the mixed salt support material prepared in the mannerdescribed above was suspended in inert conditions into 150 ml ofheptane, and the suspension was agitated for half an hour. Thesuspension was cooled to -15° C. Then 300 ml of cold titaniumtetrachloride was added and the temperature was raised slowly to +20° C.5.3 ml of an internal donor (di-isobutyl phthalate, DIBP) was added tothe reaction mixture. The temperature was raised, according to thegradient, to the boiling point of the solution. After the boiling pointof the reaction solution had been reached, the normal catalyst synthesispath was followed.

The catalyst synthesis was carried out without difficulty. The onlydifference as compared with conventional catalyst synthesis was in thecolor of the reaction solution. Thereafter, the chemical composition ofthe procatalyst was measured. The measurement results are presented inTable 4.

                  TABLE 4                                                         ______________________________________                                        Chemical compositions of magnesium-doped catalysts                                   Mol-% Mn  Weight-%                                                     Example  added       Mg     Mn     Ti  Cl                                     ______________________________________                                        1 (comp.)                                                                               0          16.0   0.0    4.4 56.0                                   2 (emb.)  3          16.8   1.2    2.9 56.9                                   3 (emb.) 10          15.3   3.8    3.3 56.2                                   4 (emb.) 30          11.1   6.0    2.6 53.3                                   5 (emb.) 60          5.7    18.6   3.2 49.1                                   6 (comp.)                                                                              100         0.1    36.3   2.3 55.0                                   ______________________________________                                    

The results showed that the amount of manganese fed in along with thesupport material correlated quite precisely with the amount of manganesedetected in the catalyst. This can be seen clearly in FIG. 5. In it themolar percentage of manganese is shown as a function of theconcentration of manganese added. The manganese concentrations in thesupport material and in the catalyst correlate almost precisely witheach other. This result shows that manganese chloride can be added to amixture of magnesium chloride and ethanol by merely melting the twosalts together.

Characterization of the Procatalyst

All of the components of the procatalyst produced were measured. It wasalso interesting to see whether manganese affected the crystal structureof the support material. Therefore X-ray diffraction patterns of all theprocatalysts were taken. In addition, the ratio of the complexedinternal donor to the total metal amount in the procatalyst wasmeasured.

In measuring the titanium concentration it was observed that there wasno substantial difference in the ability of the support material to bindtitanium into the crystal structure when the manganese concentration ofthe magnesium chloride salt was increased. In the shift from undopedmaterial to the first doped procatalyst (3 mol-%) there occurred aslight decrease from 4.4 weight-% to approx. 3 weight-%, whereafter thetitanium concentration remained unchanged as manganese was added to thesupport material (cf. Table 4).

The donor concentration was also observed by determining the di-isobutylphthalate concentration in the procatalyst. This was done because it wasnot known whether manganese was capable of binding internal donor to thesame degree as magnesium was. In particular, it was desired to seewhether a mixture made up of two salts could retain the normal donor tosupport material ratio during the synthesis. The ratios are shown inTables 5 and 6. The final proportion is also seen in FIG. 6. Accordingto the results, the ability of the support material to bind the donordecreased sharply within the middle range of the salt mixture. Thus, acatalyst doped with 10% manganese was capable of binding only 50% of theoriginal donor amount. A 60% manganese (II) chloride material, on theother hand, was capable of binding donor to the same degree as was apure magnesium chloride material.

                  TABLE 5                                                         ______________________________________                                        A comparison of the manganese amount added, the man-                          ganese concentration in the support material, and the manganese               concentration in the catalyst                                                          Mol-% Mn     Mol-% Mn                                                         added to     detected in                                                                             Mol-% Mn                                               support      support   detected                                      Example  material     material  in catalyst                                   ______________________________________                                        1 (comp.)                                                                               0           0.0       0.0                                           2 (emb.)  3           3.1       3.1                                           3 (emb.) 10           10.0      9.9                                           4 (emb.) 30           29.2      19.2                                          5 (emb.) 60           57.9      58.6                                          6 (comp.)                                                                              100          100.0     99.1                                          ______________________________________                                    

                  TABLE 6                                                         ______________________________________                                        Donor concentrations of manganese-doped procatalysts                                 Mol-%                                                                         Mn       %       Mol-% Mol-%   Ratio                                   Example                                                                              added    DIBP    DIBP  Mn + Mg D/Mn + Mg                               ______________________________________                                        1       0       23.0    0.083 0.71    0.12                                    2       3       22.2    0.080 0.71    0.11                                    3      10       12.5    0.045 0.70    0.06                                    4      30       15.5    0.056 0.57    0.10                                    5      60       18.9    0.068 0.58    0.12                                    6      100      0.4     0.001 0.67    0.00                                    ______________________________________                                         DIBP = diisobutyl phthalate                                              

The dimensions of the doped magnesium chloride crystals were determinedby taking X-ray diffraction patterns of all the catalyst samples inorder to determine the effect of manganese (II) chloride. It proved tobe possible to use manganese up to 30% without the X-ray diffractionpattern of magnesium chloride changing substantially. With theseconcentrations a normal amorphous magnesium chloride pattern wasobtained, in which there was at 15 degrees a small peak indicating theheight of the crystal and at 50 degrees a clear peak indicating thewidth of the crystal (cf. FIG. 7). At higher manganese concentrations,the X-ray pattern of manganese (II) chloride was prevalent and a morecrystalline structure was obtained. It was possible to calculate thedimensions of magnesium chloride crystals up to a 30% concentration ofmanganese. The results are shown in Table 7, and FIG. 7 shows the X-raydiffraction pattern of a catalyst sample doped with 10% manganese.

                  TABLE 7                                                         ______________________________________                                        Crystal dimensions of Mn-doped catalysts. The heights                         were measured from a peak at 15° and the widths from a peak at         50°.                                                                            Mol-% Mn      Height at                                                                              Width at                                      Example  added         15° (nm)                                                                        50° (nm)                               ______________________________________                                        1         0            <3       4.6                                           2         3            <3       5.1                                           3        10            <3       5.5                                           4        30            <3       5.2                                           5        60            --       --                                            6        100           --       --                                            ______________________________________                                    

Test Polymerization

Test polymerizations were carried out on all of the procatalysts. Atwo-liter bench reactor was used in the test polymerization. 20-30 mg ofprocatalyst was used for the test polymerization. This amount was mixedwith 620 μl of triethyl aluminum and 200 μl of a 25% solution of theexternal donor cyclohexylmethyl-dimethoxysilane (CHMDMS) in 30 ml ofheptane. The polymerizations were carried out at +70° C. and at apropylene monomer pressure of 10 bar. The partial pressure of hydrogenduring the polymerization was 0.2 bar. The polymerization was continuedfor 3 hours. The activity was measured on the basis of thepolymerization yield. The soluble part of the polymer was measured byevaporating a measured portion out from the polymerization solution.

As has been stated, the activity was determined by test polymerizing allof the catalysts in the same conditions. Table 8 shows thepolymerization results. Activity is here expressed both in kg PP/g cat.and in kg PP/g Ti. The results are also shown graphically in FIG. 8.

                  TABLE 8                                                         ______________________________________                                        Activity of Mn-doped catalysts                                                         Mol-% Mn    Activity   Activity                                      Example  added       kg PP/g cat.                                                                             kg PP/g Ti                                    ______________________________________                                        1 (comp.)                                                                               0          14.3       325                                           2 (emb.)  3          14.1       486                                           3 (emb.) 10          20.0       606                                           4 (emb.) 30          12.8       492                                           5 (emb.) 60          8.4        262                                           6 (comp.)                                                                              100         1.0         43                                           ______________________________________                                    

Mn-doping seemed to have a crucial effect on the activity of thecatalysts. Doping with 3% manganese yielded almost the same result as anundoped procatalyst, if only the activity unit kg PP/g cat. isconsidered, but caused an increase up to 25% in the activity whenexpressed in kg PP/g Ti. The activity increase was greatest when amaterial doped with 10% manganese was used. In this case activities upto 20 kg PP/g cat. were obtained. Expressed in kg PP/g Ti, the activityincrease was in the order of 100%. With higher doping concentrationsthere was an almost linear activity decrease with increasing manganeseconcentrations. When pure manganese (II) chloride was used instead ofmagnesium chloride, the activity was only 10% of the original activity.

Characterization of the Polymer Samples

Bulk densities and particle size distributions were determined on thepolymer samples obtained. Isotacticity was determined by heptaneelution, and the isotactic index was determined from the resultsobtained from evaporation residue measurements. The melt index wasdetermined at 230° C. by using a 2.16 kg weight. To observe the effectof the salt mixture on polydispersity, molecular weight distributionswere determined on all of the polymer samples.

First, the isotacticity and the isotactic indices of the polymer sampleswere measured. The results are presented in Table 9 and are showngraphically in FIG. 9.

                  TABLE 9                                                         ______________________________________                                        Isotactic indicators of polymer samples produced using                        Mn-doped procatalysts                                                                                    Evaporation                                                                             Isotactic                                       Mol-% Mn  Isotacticity                                                                            residue   index                                    Example                                                                              added     (%)       (g)       (%)                                      ______________________________________                                        1 (comp.)                                                                             0        99.3      2.4       98.8                                     2 (emb.)                                                                              3        97.6      6.1       96.2                                     3 (emb.)                                                                             10        98.4      4.1       97.7                                     4 (emb.)                                                                             30        99.0      3.1       98.2                                     5 (emb.)                                                                             60        98.5      3.0       97.3                                     6 (comp.)                                                                            100       90.5      7.7       71.2                                     ______________________________________                                    

The results indicate that isotacticity remained stable at a high levelup to high Mn-doping percentages. Only at a concentration which wasabove 60 mol-% Mn was there a drastic decrease in isotacticity. Whenpure manganese (II) chloride was used as the support material, theisotactic index dropped to 70%. At lower doping concentrations (below 60mol-% manganese) the isotactic index varied only slightly, being withinthe range 97-98%.

Next, the particle size distributions of the polymers were determined. Acatalyst particle without mechanical strength usually collapses duringpolymerization, and the small products of the collapse also producefines in the polymer produced. Therefore the particle size distributionwas determined on all of the polymer samples in order to determine themechanical strength of the catalyst particles. The results are shown inTable 10.

                                      TABLE 10                                    __________________________________________________________________________    Particle size distributions of the polymers produced                          using Mn-doped catalysts                                                            Mn 2.0 1.0                                                                              0.5 0.18                                                                             0.10                                                                              0.056                                                                            0.036                                           Example                                                                             %  mm  mm mm  mm mm  mm mm  Fines                                       __________________________________________________________________________    1 (comp.)                                                                            0 10.0                                                                              64.8                                                                             19.3                                                                              3.9                                                                              1.5 0.5                                                                              --  --                                          2 (emb.)                                                                             3 46.5                                                                              50.9                                                                             2.4 0.1                                                                              0.1 -- --  --                                          3 (emb.)                                                                            10 10.9                                                                              65.4                                                                             21.6                                                                              1.8                                                                              0.2 0.1                                                                              --  --                                          4 (emb.)                                                                            30 95.9                                                                              4.0                                                                              --  -- 0.1 -- --  --                                          5 (emb.)                                                                            60 8.6 32.4                                                                             46.7                                                                              9.6                                                                              1.7 1.0                                                                              0.1 --                                          __________________________________________________________________________

The polypropylene material produced using Mn-doped catalysts had a verylow fines content when the doping percentage was below 30%. This isclearly visible also in FIG. 10. Compared with an undoped catalyst, thecatalyst containing manganese 3% contained hardly any particles withdiameters smaller than 1 mm. A catalyst having a doping percentage of30% yields even better results.

The particle size distribution measurements correlate well with theobservations made regarding the morphology of the support material. Goodmorphology was obtainable with doping values up to 30%, whereafter thepolymer particles showed a collapsing behavior similar to that ofprocatalyst particles, whereby a large proportion of fines was produced.The best results with respect to the particle size distribution wereachieved with a magnesium doping percentage of 30. The particle sizedistribution of this polymer sample is shown in FIG. 11.

The bulk densities of the polymer materials are listed in Table 11. Thevalues seem to decrease as the Mn-doping percentages increase. Thisseems to be due, first, to the fact that an increasing particle sizeautomatically causes a decrease in the bulk density and, second, to thefact that a strongly doped catalyst produces irregular particles whichreduce the bulk density. The bulk densities of the polymer samples areshown as a function of the Mn-doping concentration also in FIG. 10.

                  TABLE 11                                                        ______________________________________                                        Bulk densities of polymer samples produced using Mn-                          doped procatalysts                                                            Example    Mol-% Mn added                                                                             Bulk density g/ml                                     ______________________________________                                        1           0           0.44                                                  2           3           0.44                                                  3          10           0.37                                                  4          30           0.37                                                  5          60           0.43                                                  6          100          0.29                                                  ______________________________________                                    

The melt indices of the polymer samples are shown in Table 12. They seemto vary very little within a range of 0-60% Mn. Thus it can be statedthat the melt index measurements yielded rather satisfactory results,although at 10% the melt index drops somewhat.

                  TABLE 12                                                        ______________________________________                                        Melt indices of polymer samples produced using Mn-                            doped procatalysts                                                            Example    Mol-% Mn added                                                                             Melt index (2.16 kg)                                  ______________________________________                                        1           0           10.0                                                  2          3            10.1                                                  3          10            6.8                                                  4          30           13.2                                                  5          60           12.5                                                  6          100          approx. 3000                                          ______________________________________                                    

The specific target of interest in the present work is the molecularweight distribution of the polymer produced, for the idea is to producein the catalyst differentiated active sites and thereby to form in thepolymerization polymer chains of a variety of lengths. The analyticalresults obtained are listed in Table 13, and they are shown graphicallyin FIG. 12.

                  TABLE 13                                                        ______________________________________                                        Molecular weight distributions of polymer samples                             produced using Mn-doped procatalysts                                          Example Mol-% Mn   M.sub.n  M.sub.w                                                                              M.sub.v                                                                              D                                   ______________________________________                                        1        0         85900    286000 242000 3.3                                                    83200    297000 248000 3.6                                 2        3         52900    328000 247000 6.2                                                    53700    324000 244000 6.0                                 3       10         57100    382000 285000 6.7                                                    56400    392000 288000 7.0                                 4       30         53600    298000 229000 5.6                                                    53600    306000 237000 5.7                                 5       60         59400    297000 233000 5.0                                                    58900    292000 228000 5.0                                 6       100        31200    154000 123000 4.9                                                    30600    161000 127000 5.3                                 ______________________________________                                    

As can be seen in FIG. 12, the entire molecular weight, but especiallythe viscosity average molecular weight (M_(v)) and the weight averagemolecular weight (M_(w)), increase sharply when the molar percentage ofmanganese in the procatalyst increases from 0 to 10. At higher dopingconcentrations, however, there occurs a decrease of the molecularweight. The low molecular weights obtained with pure manganese (II)chloride may explain why the polymer products have a low isotacticityand a high melt index. The number average molecular weight (M_(n)) dropssharply when the doping concentration increases from zero to three % Mn,but remains thereafter almost unchanged up to 60% Mn.

Polydispersity, i.e. the ratio of weight average molecular weight tonumber average molecular weight, was also calculated from the molecularweight measurement results. FIG. 13 shows the polydispersity values as afunction of the manganese concentration in the procatalyst.Polydispersity increased from the conventional value 3 up to 7 when themanganese concentration in the procatalyst increased from zero to 10mol-% manganese (calculated from Mn+Mg). Thereafter, polydispersitydropped to a constant value of 5. FIG. 14 shows a comparison between amolecular weight distribution obtained with a polymer produced using anundoped procatalyst and the molecular weight distribution of a polymerproduced using a procatalyst doped with 10% manganese.

The effect of a magnesium chloride support material doped with manganesecan be seen as follows:

1. A very good polymer product morphology is obtained when theconcentration of manganese (II) chloride is below 30%. Specifically withthis manganese concentration the very best particular size distributionis obtained, in which case the polymer contains hardly any fines.

2. With the use of a doped procatalyst, large catalyst particles with ahigh mechanical strength were obtained, which for its part affected theabove-mentioned good particle size distribution of the polymer.

3. The best activity was obtained with a manganese doping concentrationof 10 mol-%, in which case the activity was up to 25% higher than theactivity obtained using an undoped catalyst. A good activity wasobtained without a decrease in isotacticity.

4. Doping also affected the molecular weight distribution by broadeningit. Since obtaining a polymer with a broad molecular weight distributionhad been set as a specific object of the invention, the optimalconcentration of the doping metal was determined in this respect. Thebest results were obtained using a procatalyst doped with approx. 10mol-% manganese (calculated from the total molar amount of manganese andmagnesium). In this case, polydispersity increased to 7 from theconventional value 3.

We claim:
 1. An olefin polymerization catalyst comprising:(1) aprocatalyst component prepared by:(a) contacting magnesium chloride withmethanol and/or ethanol and melting the mixture in the presence ofmanganese (II) halide added in an amount of at least about 0.1% and atmost about 50%, based on the total molar amount of magnesium chlorideand manganese (II) halide, thus forming a molten mixture, (b) atomizingthe molten mixture and solidifying it by cooling to produce supportmaterial particles, and (c) reacting the support material particles withtitanium tetrachloride.
 2. The polymerization catalyst according toclaim 1, wherein the manganese (II) halide is manganese (II) chloride.3. The polymerization catalyst according to claim 1, wherein theconcentration of manganese (II) halide is at least about 5% of the totalmolar amount of magnesium chloride and manganese (II) halide.
 4. Thepolymerization catalyst according to claim 1, wherein the concentrationof manganese (II) halide is at most about 40% of the total molar amountof magnesium chloride and manganese (II) halide.
 5. The polymerizationcatalyst according to claim 1, wherein the amount of manganese (II)halide is in the range of about 8-15% of the total molar amount ofmagnesium chloride and manganese (II) halide, thereby maximizing theactivity of the catalyst and providing a broad molecular weightdistribution of the polymer.
 6. The polymerization catalyst according toclaim 1, wherein the manganese (II) halide concentration is about25-35%, thereby enhancing the effect of the catalyst on the productionof large polymer particles.
 7. The polymerization catalyst according toclaim 1, wherein the procatalyst component comprises about 10-20%magnesium, about 1-10% manganese, about 2-4% titanium, and at minimumabout 45-60% chloride, calculated from the total weight of theprocatalyst.
 8. The polymerization catalyst according to claim 1,wherein step (c) further comprises reacting the magnesium chloridesupport material with an internal electron donor.
 9. The polymerizationcatalyst according to claim 8, wherein the concentration of internaldonor is about 10-25% by weight of the catalyst.
 10. The polymerizationcatalyst according to claim 1, further comprising (2) an organometalliccocatalyst.
 11. The polymerization catalyst according to claim 10,further comprising an external electron donor.
 12. A method for theproduction of a procatalyst component for an olefin polymerizationcatalyst, comprising:(a) contacting and mixing magnesium chloride, withmethanol and/or ethanol, and about 0.1% to about 50% of manganese (II)halide, based on the total amount of magnesium chloride and manganese(II) halide, and melting the mixture to form a molten mixture, (b)atomizing the molten mixture, and solidifying it by cooling to producesupport material particles, and (c) reacting the support materialparticles with titanium tetrachloride.
 13. The method according to claim12, wherein steps a) and b) are carried out by: (i) suspending afinely-divided magnesium chloride and a finely-divided manganese (II)halide into an inert, heat-resistant medium; (ii) adding to thesuspension methanol and/or ethanol, and heating until the mixture of thesalts and the alcohol becomes liquefied or melts to form melt drops inthe medium; and (iii) contacting the medium and its melt drops with acold material which preferentially dissolves the medium and solidifiesthe melt drops to form finished support material particles.
 14. Themethod according to claim 12, wherein the manganese (II) halide ismanganese (II) chloride.
 15. The method according to claim 12, whereinthe manganese (II) halide is added in step a) in an amount of at leastabout 5% of the total molar amount of magnesium chloride and manganese(I) halide.
 16. The method according to claim 12, wherein the manganese(II) halide is added in step a) in an amount of at most about 40% of thetotal molar amount of magnesium chloride and manganese (II) halide. 17.The method according to claim 12, wherein step c) is carried out bycausing the support material particles to react with an internalelectron donor.
 18. A method for producing polypropylene, comprisingpolymerizing propylene in the presence of a polymerization catalystaccording to claim
 1. 19. The method for producing polypropyleneaccording to claim 18, wherein said polypropylene has a broad molecularweight distribution.
 20. The method for producing polypropyleneaccording to claim 18, wherein said catalyst further comprises anorganoaluminum compound and an external electron donor.
 21. Thepolymerization catalyst according to claim 5, wherein the amount ofmanganese (II) halide is about 10% of the total molar amount magnesiumchloride and manganese (II) halide.
 22. The polymerization catalystaccording to claim 6, wherein the concentration of manganese (II) halideis about 30% of the total molar amount magnesium chloride and manganese(II) halide.
 23. The polymerization catalyst according to claim 8,wherein said internal electron donor is an aromatic ester.
 24. Thepolymerization catalyst according to claim 23, wherein said aromaticester is di-isobutyl phthalate.
 25. The polymerization catalystaccording to claim 10, wherein said organometallic catalyst is atrialkyl aluminum.
 26. The polymerization catalyst according to claim25, wherein said trialkyl aluminum is triethyl aluminum.
 27. Thepolymerization catalyst according to claim 11, wherein said externalelectron donor is selected from the group consisting of a silane,cineole, and an ether.
 28. The polymerization catalyst according toclaim 27, wherein said electron donor is selected from the groupconsisting of cyclohexyl-methyl-dimethoxysilane (CHMDMS), cineole anddiphenyl-dimethoxysilane (DPDMS).
 29. The method according to claim 17,wherein said internal electron donor is an aromatic ester.
 30. Themethod according to claim 29, wherein said aromatic ester is di-isobutylphthalate.